Reviews in Fish Biology and Fisheries

, Volume 6, Issue 2, pp 125–137 | Cite as

Lessons for stock assessment from the northern cod collapse

  • Carl Walters
  • Jean-Jacques Maguire


Fisheries assessment scientists can learn at least three lessons from the collapse of the northern cod off Newfoundland: (1) assessment errors can contribute to overfishing through optimistic long-term forecasts leading to the build-up of overcapacity or through optimistic assessments which lead to TACs being set higher than they should; (2) stock size overestimation is a major risk when commercial catch per effort is used as an abundance trend index, so there is continued need to invest in survey indices of abundance trend no matter what assessment methodology is used; and (3) the risk of recruitment overfishing exists and may be high even for very fecund species like cod. This implies that harvest rate targets should be lower than has often been assumed, especially when stock size assessments are uncertain. In the end, the high cost of information for accurate stock assessment may call for an alternative approach to management, involving regulation of exploitation rate via measures such as large-scale closures (refuges) that directly restrict the proportion of fish available to harvest. Development of predictive models for such regulatory options is a major challenge for fisheries assessment science.


Stock Assessment Assessment Science Harvest Rate Stock Size Regulatory Option 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Anon. (1977) Repost of the Standing Committee on Research and Statistics (STACRES). Appendix I, Report of Assessment Subcommittee, p.54. Int. Comm. Northwest Atlantic Fisheries, Redbook 1977. 116pp.Google Scholar
  2. Baird, J.W., Bishop, C.A., Brodie, W.B. and Murphy, E.F. (1992) An assessment of the cod stock in NAFO divisions 2J3KL. NAFO Sci. Council Res. Doc. 92/18, Ser. No. N2063.Google Scholar
  3. CAFSAC (1987) Canadian Atlantic Fisheries Scientific Advisory Committee, Annual Report for 1986 (Volumn 9). Dartmouth, Canada: Dept Fisheries and Oceans.Google Scholar
  4. Cooke, J.G., and Beddington, J.R. (1985) The relationship between catch rates and abundance in fishes. IMA J. Math. Appl. Med. Biol. 2, 1–15.Google Scholar
  5. Deriso, R.B. (1987) Optimal F0.1 criteria and their relationship to maximum sustainable yield. Can. J. Fish. aquat. Sci. 44 (Suppl. 2) 339–48.Google Scholar
  6. Dugan, J.F. and Davis, G.E. (1993). Applications of marine refugia to coastal fisheries management. Can. J. Fish. aquat. Sci. 50, 2029–42.Google Scholar
  7. Finlayson, A. (1994) Fishing for Truth: A Sociological Analysis of Northern Cod Stock Assessments from 1977–1990. St John's Nfld: Inst. Social and Economic Res., Memorial University. 176 pp.Google Scholar
  8. Fleming, A.M. (1965) Trends in catch, age, and size of cod from the commercial longline fishery at Bonavista, Newfoundland, 1952–1962. J. Fish. Res. Bd Can., 22, 465–74.Google Scholar
  9. Gavaris, S. (1988) An adaptive framework for the estimation of population size. CAFSAC (Can. Atl. Fish. Sci. Adv. Comm.) Res. Doc. 88/29.Google Scholar
  10. Grecco, V. and Overholtz W.J. (1990) Causes of density-dependent catchability for Georges Bank haddock (Melanogrammus aeglefinus). Can. J. Fish. aquat. Sci. 47, 385–94.Google Scholar
  11. Harris, L. (1990) Independent review of the stae of the northern cod stock. Ottawa: Communications Directorate, Canadian Dept Fisheries and Oceans. 154 pp.Google Scholar
  12. Hilborn, R. and Walters C. (1992) Quantitative Fisheries Stock Assessment and Management: Choice, Dynamics, and Uncertainty. New York: Chapman & Hall. 604 pp.Google Scholar
  13. Hutchings, J. and Myers, R.A. (1994) What can be learned from the collapse of a renewable resource? Atlantic cod, Gadus Morhua, of Newfoundland and Labrador. Can. J. Fish. aquat. Sci. 51, 2126–46.PubMedGoogle Scholar
  14. ICES (1988) Report of the workshop on methods of fish stock assessment. Copenhagen, Denmark: Int. Council for the Exploration of the Seas.Google Scholar
  15. Lear, W.H. and Parsons, L.S. (1993) History and management of the fishery for northern cod in NAFO Divisions 2J, 3K, and 3L In Parsons, L.S. and Lear, W.H., eds. Perspectives on Canadian marine fisheries management. Can. Bull. Fish. aquat. Sci. No. 226, pp. 55–89.Google Scholar
  16. McGuire, T.R. (1991) Science and the destruction of a shrimp fleet. Mar. anthropol. Stud. 4, 32–55.Google Scholar
  17. Myers, R.A. and Barrowman, N.J. (1994) Is fish recruitment related to spawner abundance. ICES CM 1994/G: 37, Ref. H.Google Scholar
  18. Myers, R.A., Drinkwater, K.F., Barrowman, N.J. and Baird, J.W. (1993) Salinity and recruitment of Atlantic cod (Gadus morhua) in the Newfoundland region. Can. J. Fish. aquat. Sci. 50, 1599–1609.Google Scholar
  19. Myers, R.A., Rosenberg, A.A., Mace, P.M., Barrowman, N. and Restrepo, Y.R. (1994) In search of thresholds for recruitment overfishing. ICES J. mar. Sci. 51, 191–205.Google Scholar
  20. NAFO (1991) Northwest Atlantic Fisheries Organization, Scientific Council Reports for 1981. Dartmouth, Canada.Google Scholar
  21. Patterson, K. (1992) Fisheries for small pelagic species: an empirical approach to management targets. Rev. Fish Biol. Fisheries 2, 321–38.Google Scholar
  22. Pauly, D. (1994) On the Sex of Fish and the Gender of Scientists (Fish and Fisheries Series 14). London, UK: Chapman and Hall. 250 pp.Google Scholar
  23. Pitcher, T. and Hart, P.J.B. (1982) Fisheries Ecology. London: Chapman and Hall. 414 pp.Google Scholar
  24. Restrepo, V.R., Hoenig, J.M., Powers, J.E., Baird, J.W. and Turner, S.C. (1992) A simple simulation approach to risk and cost analysis, with applications to swordfish and cod fisheries. Fishery Bull. 90, 736–48.Google Scholar
  25. Rivard, D. (1989) Overview of the systematic, structural and sampling errors in cohort analysis. Am. Fish. Soc. Symp. 6, 49–65.Google Scholar
  26. Steele, D.H., Andersen, R. and Green, J.M. (1992) The managed commercial annihilation of northern cod. Newfoundland Stud. 8, 34–68.Google Scholar
  27. Swain, D.P. and Sinclair, A.F. (1994) Fish distribution and catchability: what is the appropriate measure of distribution? Can. J. Fish. aquat. Sci. 51, 1046–54.Google Scholar
  28. Swain, D.P., Nielsen, G.A., Sinclair, A.F. and Chouinard, G.A. (1994) Changes in catchability of Atlantic cod (Gadus morhua) to an otter trawl fishery and research survey in the southern Gulf of St. Lawrence. ICES J. mar. Sci. (in press).Google Scholar
  29. Tobin, B. (1995) Speaking for the fish. Fisheries 20(7), 18–19.Google Scholar
  30. Walters, C.J. and Ludwig, D. (1987) Adaptive management of harvest rates in the pressure of a risk averse utility function. Nat. Res. Model. 1, 21–37.Google Scholar
  31. Walters, C.J. and Ludwig, D. (1994) Calculation of Bayes posterior probability distributions for key population parameters. Can. J. Fish. aquat. Sci. 51, 713–22.Google Scholar
  32. Walters, C.J. and Punt, A. (1994) Placing odds on sustainable catch using virtual population analysis and survey data. Can. J. Fish. aquat. Sci. 51, 946–58.Google Scholar

Copyright information

© Chapman & Hall 1996

Authors and Affiliations

  • Carl Walters
    • 1
  • Jean-Jacques Maguire
    • 2
  1. 1.Fisheries Centre, University of British ColumbiaVancouverCanada
  2. 2.Department of Fisheries and OceansQuebec CityCanada

Personalised recommendations